Radioactive source holder



United States Patent O 3,045,701 RADACTIVE SURCE HLDER Eugene P. Thomas,Catonsville, Md., assignor to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 12, 1958,Ser. No. 760,791 7 Claims. (Cl. Z50-406) This invention relates toshielded devices for holding a source of radioactive material anddirecting a beam of radiant energy therefrom for medical therapy andother purposes; and more particularly to such source holder devices ascomprise a main body for containing the radioactive source and shieldingthe same in a safe manner when in a repose position, and a radiationemergence portion into which portion said source is moved for registrywith a radiation emergence laperture therein.

It is a prime object of the present invention to provide a source holderdevice of the above general type having improved means for effectingactuation of the radioactive source from its repose position to itsactive position whereby such actuation is greatly facilitated andfail-safe operation of the device is assured.

It is another object of the invention to provide a source holder deviceof the above general type having improved means for shielding theguideway along which said source is moved.

lt is a Still further object of the present invention to provide asource holder device of the above general type having improved means forlocating the path of the radiation beam collirnated by the radiationemergence aperture.

It is another object of the present invention to provide a source holderdevice of the above general type having improved means enabling loadingof the device with the radioactive source material in a facile and safemanner.

Other objects and advantages of the invention will become apparent fromthe following detailed description of the invention when taken inconnection with the accompanying drawing, in which the single figure isa side sectional view, several components being in outline, of thesource material holder embodying the invention.

Referring to the drawing, the source holder embodying the invention isprimarily, though not necessarily, intended for employment with acobalt-60 source, and, to provide adequate shielding with minimum bulk,includes a generally spherical-shaped hollow metal container 10 filledwith `shielding material 11, such as lead, in which is centrally locateda source capsule 12 when in a fully shielded position at a reposestation. One end of the container 1t) is blunt and enclosed by asubstantially disc-shaped front wall 14 to which is attached a cylindermember 16 extending inwardly of container 10 centrally of wall 14. Anend member 1S, attached to the innermost end of the cylinder member 16,is provided with a fluid pressure port 20 to enable ingress and egressof iiuid under pressure to and from a pressure chamber 21 via alabyrinth conduit 24, embedded in the material 11, and an externalfitting 26, for actuation of the source capsule 12 in manner as will beset forth in detail hereinafter.

A hollow cylinder member 28 is rotatably mounted in cylinder member 16to act as a cylindrical guideway for directing movement of the sourcecapsule 12 from its repose position in which it is shown in the drawingto an operative position hereinafter defined, and to define the hub of anovel radiation emergence portion 30 of the source holder.

The radiation emergence portion 3@ includes a substantially cylindricalmetal shell 32 filled with a shielding Y ICC material 34, such as lead,the central portion of shell 32 being defined by an extension of thecylindrical member 2S which is attached to such shell by means such aswelds (not shown). An end of the shell 32 adjacent to the front wall 14of the container 1l) is defined by an annular end wall 36 and bearingrace support member 38 encircling member 28, each component beingattached suitably one with the other to provide a fluid tight containeradapted for holding the shielding material 34 when introduced initiallythereinto in its molten state. The periphery of the shell 32 is definedby an elongated ring member 4t), and the other end of such shell isdefined by a portion including an annular flange 42 attached at itsouter periphery to ring member 40, an integral frustroconical portion 44and an end wall 46 attached at its inner periphery to cylinder member28.

The source capsule l2 is carried in an end portion 47 of an elongatedpiston assemblage 48, such end portion being of a special grade of highlead (30%) bearing bronze which will not gall in contact with cylindermember 28 which is of stainless steel, and the remainder of pistonmember 48 is hollow and filled with a shielding material such as lead.Lubrication is obtained by a dry film type lubricant such as graphite inepoxy binder.

According to a feature of the invention, bronze piston rings 49 areprovided on the end portion 47 of piston member 4S for substantialsealing engagement with the inner `wall of cylinder member 28 while atthe same time providing for slight clearance therebetween to enable somefiuid under pressure at a controlled rate to leak past such ringsbetween the piston member 48 and the inner wall of said cylinder member,for reasons which hereinafter will be set forth.

End portion 47 of piston 48 is further provided with a cylindricalsocket 52 terminating at an annular shoulder 53 formed in portion 47 atthe juncture of such socket 52 with an emergence port 64. Socket 52 isadapted for registry, in a displaced position of piston 48, with anaperture 54 defined by a sleeve member 56 associated with portion 3b andextending radially outward from corresponding apertures in cylindermember 28 at its inner end and in ring member 40 at its outer end.Registry of socket 52 with sleeve member 56 enables the source capsule12 to be inserted into and ejected out of such socket via the aperture54, at any angular position, according to the rotary position of portion30 with respect to container 10. A lead plug 60, removably secured by aset screw 61, normally fills the aperture 54 subsequent to insertion ofthe source capsule 12 into socket 52.

The emergence port 64 opens from the socket 52 radially of piston member4S oppositely to the open end of socket 52, for registry with aradiation emergence aperture 66 formed by a hollow -member 67 extendingradially outwa-rd from cylinder member 28 to sleeve member `4t), foremergence of radiation from capsule 12 to the exterior of the sourceholder when the piston assemblage 48 is fluid pressure actuated toattain such registry. As a feature of the invention, the radiationemergence aperture 66 is -disposed in alignment with the loadingaperture 54 to enable an instrument to be inserted through the emergenceaperture 66 and port 64 -to force the source capsule out throughaperture 54 during unloading, should such capsule become jammed at thistime. A spring detent means (not shown) preferably is employed torestrain the source capsule 12 within the socket 52 and therebyyieldably retain same in place against undesirable shifting within suchsocket.

A return spring assemblage 69, including a plurality of coaxiallyarranged helical compression springs, is arranged to return the pistonassemblage 48 to the repose position in which it is shown in the drawingand in which the source capsule 12 is completely shielded by material 11of container 10 and by material 50 within piston assemblage 48. In suchrepose position, a source of visible light in the form of a bulb 70,carried by piston member 48, is brought into registry with the emergenceaperture 66 to provide for focusing such aperture by visible light withthe area of a patient or target to be subjected to radiation. In accordwith the feature of the invention, it will be appreciated that suchdirect registry of bulb 70 with emergence aperture 66 provides `forreliable focusing without resort to mirrors or reflecting elements whichmight be subject to misalignment periodically.

To enable the emergence portion 30 and piston member 48 to be turnedabout the axis of such piston member for selective orientation of theradiation emergence aperture 66 while at the same time relieving thehollow cylinder member 28 of the load of such portion and providing 4arelatively frictionless rotary connection, a tapered roller bearingVassemblage 71 is interposed radialwise between bearing race support4member 38 and a portion of wall 14 of container 10, and a ball-typethrust bearing assemblage 72 extends radialwise in interposition betweenwall 14 and such portion 30. An outer raceway 73 of assemblage 72 isremovably secured by screws 74 to wall 114, and the inner raceway 75 ofassemblage 72 is attached to a plurality of bolts 76 which extendthrough the portion 30, including an annular end member 77 attached toend wall 46 of such portion 30. By means of nuts 78, the portion 36 isremovably attached to container 10 through the medium of they bolts 76and the thrust bearing assemblage '72.

To enable accurate and facile rotary movement of the beam emergenceportion 30, relative to container 10, a handwheel 82 is provided whichis rotatably supported on the outer periphery f end member 77 throughthe `medium of rollers 83 and is connected to container 10 through `agear train. The gear train includes a large ring gear 84 attached tohandwheel 82, an engaging small gear S attached to one end of arotatable shaft 86 journaled in end member 77 and extending throughmaterial 34 and through end wall 36, a gear 87 attached to the oppositeend of shaft 86, and a gear 88 attached to the front wall 14 ofcontainer 10. An idler gear, not shown, may be suitably arranged in suchgear train where it is desired to change the directionality relationshipbetween rotary movement of shell 32 and that of the handwheel 82. Itwill be apparent by reference to the drawing that turning movement ofshaft 86 around its own axis through the medium of handwheel 82 andgears 84, 85 will cause gear 87 to roll around gear 88 and carry suchshaft 86 and shell 32 with it, thereby turning the emergence aperture 66about the axis of the piston member 48 which will also be turnedcorrespondingly during the turning of cylindrical member 28 in which itis disposed.

To assure that the emergence portion 30 may not accidentally be movedfrom a `selected rotary position 'relative to container 10, a frictionassemblage (not shown) may be provided for cooperation between portion30 and `such as wall 14 of container 10.

The yspring assemblage 69` extends into the end of a hollow extendedportion 100 of piston assemblage 48 and into contact at its one end withan interior wall 1 of such piston assemblage. The opposite end of thespring assemblage is in thrust engagement with an end Wall 104 of acylindrical spring container '106 which is attached at a flanged end 167to the end member 77. A cover 108, attached at 109 to spring container106, encases same and covers a substantial front portion of thehandwheel l`82 primarily to enhance the appearance of the source holder.

A tab 116, attached to the end of the hollow extended outward therefromthrough a longitudinal slot 111 in spring container 106. During rotarymovement of the emergence portion 30 by manipulation of the handwheel 82for orientation of the radiation emergence aperture, the springcontainer 166 attached to end member 77 will turn in unison with theshell 32, and through contact of a side wall of the -slot 111 with thetab 110, turning of the piston assemblage 48 in unison with portion 30for maintaining proper registry of emergence ports 64 and 66 in unisonwith portion 30 will be assured. In addition, an elongated slot 114 inregistry with slot 111 is formed in the cover 168 for accommodation ofthe tab during iluid pressure yactuation of the piston assemblage 48 toenable the tab 11G to project outwardly therefrom to serve as indicationthat the source capsule 12 is in its operative position at the radiationemergence aperture 66. Upon return of the piston assemblage 48 to itsrepose position in which it is shown in the drawing, the tab 110 willbecome disposed within cover 168 to indicate that the source capsule 12is disposed in its fully shielded inoperative position. The tab 116,when in its extended position within slot 114, may also serve as a meanswhereby force can be applied to the piston member 48 to eiect return ofthe source capsule 12 to its repose position within housing 10` in theremote event that the spring assemblage 69 should fail in this regard.

The spring assemiblage 69, in addition to its normal piston-returningfunction, represents a fail-safe arrangement to assure return of `thepiston assemblage 48 automatically, should pressure of uid in the source(not shown) supplying chamber 21 become depleted accidental* ly at atime when the piston assemblage 48 was positioned for registry of sourcecapsule 12 with the emergence aperture 66. In addition, should it befound impossible to eiiect release of iluid under pressure vfrom thechamber 21 by way of the conduit 24 and iitting 26, due, for example, toa stuck control valve (not shown), at a time when the piston member 48is disposed for registry of the capsule 12 with the emergence aperture66, in accord with additional fail-safe feature of the invention, fluidunder pressure in the chamber 21 will leak past the somewhat loosely tpiston rings 49 and the piston assemblage 48 lthrough the cylindricalmember 28 to the atmosphere by way of such as emergence aperture 66, andthereby permit the spring assemblage 69 to automatically return thepiston assemblage 48 and source capsule 12 to its fully shielded reposeposition.

Certain features of the present invention are disclosed Ibut not claimedin copending US. patent application Serial No. 748,350, tiled July 14,1958, entitled Teletherapy Device, by Robert L. Guentner and Edward F.Moran, which application is assigned to the assignee of the presentapplication.

Since changes may be made in the abovedescribed construction anddifferent embodiments of the invention may be made without departingfrom the spirit and scope thereof, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

I claim as my invention:

1. In a radiation source material holder, the combination of meansdefining a cylindrical guideway, a uid pressure actuated pistonassemblage slidably mounted in said guideway for conveying a radioactivesource material from a fully-shielded position to an active position foremission of radiation from such holder, spring means biasing said pistonmeans toward its fully shielded position, said piston assemblage havingIradial clearance with respect to the wall of said guideway whereby uidunder pressure will leak past said piston assemblage at a controlledrate to permit said spring means to automatically return same to itsfully shielded position in the event uid under presin a normal manner.

2. A radioactive source material holder comprising shielded enclosuremeans having a radiation emergence aperture therein, a radioactivesource material capsule, a light bulb, and conveying means within saidenclosure means carrying said radioactive source material capsule andsaid light bulb for selective registration with said emergence aperture.

3. A radiation source material holder comprising a lirst shieldedportion having a cavity therein open to its exterior; a second shieldedportion having an opening in registration with said cavity and aradiation emergence aperture extending radially outward therefrom; andpiston means having a radioactive source carrying end normally disposedat the inner end of said cavity, a focusing-light carrying end normallyydisposed in registry with said radiation emergence aperture, and anintermediate radiation shielding portion, said piston means beingactuable by fluid under pressure along said cavity and along saidopening to disestablish and establish registry with said radiationemergence aperture of said focusing-light carrying end and saidradioactive source carrying end, respectively.

4. A radioactive source material holder comprising shielded enclosuremeans defining a cylindrical guideway with oppositely-arranged radiationemergence and loading apertures extending radially outward therefrom tothe exterior of such holder, and piston means slidably disposed in saidguideway for conveying a radioactive source material from a fullyshielded position to a position in registry with said apertures, saidpiston means having a cavity formed therein for registry with theloading aperture to receive a radioactive source material capsulethereby, and having a port opening into said cavity for registrationwith said radiation emergence aperture to facilitate radiation from suchsource capsule.

5. A radioactive source material holder comprising a first shieldedenclosure; a second shielded enclosure having oppositely-arrangedradiation emergence and loading apertures extending outward therefrom toits exterior, said second shielded enclosure being rotarily mounted onsaid irst enclosure for rotary movement of said apertures about an axiswith respect to which said apertures extend radially; piston means forconveying a radioactive source capsule material along said axis from afully shielded position within said first shielded enclosure to anactive position within said second shielded enclosure, said piston meanshaving a cavity formed therein for registry with said loading apertureto receive `and exit said source material capsule thereby, and having aport opening into said cavity for registration with said radiationemergence aperture; `and means for effecting turning movement of saidpiston means correspondingly with turning movement of said secondenclosure to maintain proper alignment for establishment of theaforesaid registries irrespective of the rotary position of said secondenclosure.

6. A radiation source material holder comprising enclosure meansdefining a shielded cylindrical guideway, piston means normally operatedby uid under pressure and slidably mounted in said enclosure means forconveying a radioactive source material along said guideway betweenfully shielded and partially shielded positions, return spring means forsaid piston means, and rigid means attached to said piston means andextending to the exterior of said enclosure means whereby said pistonmeans may be actuated manually to convey said source material to itsfully shielded position in event of failure of the normally operativemeans for actuating said piston means.

7. A radioactive source material holder comprising a lirst shieldedenclosure; a second shielded enclosure having oppositely-arrangedradiation emergence and loading apertures extending outward therefromtoits exterior, said second shielded enclosure `being rotarily mountedon said rst enclosure for rotary movement of said apertures about an-axis with respect to which said apertures extend radially; piston meansfor conveying a radioactive source capsule material along said axis froma fully shielded position Within said irst shielded enclosure to anactive position within said second shielded enclosure, said piston meanshaving a cavity for-med therein for registry with said loading apertureto receive and exit said source material capsule thereby, and having aport opening into said cavity for registration with said radiationemergence aperture; means for electing turning movement of said pistonmeans correspondingly with turning movement of said second enclosure tomaintain proper alignment for establishment of the aforesaid registriesirrespective of the rotary position of said second enclosure, andmanually operable means including handwheel and gear means cooperab'lebetween the aforesaid first and second shielded enclosures for effectingrotary movement of the latter with respect to the former.

References Cited in the iile of this patent UNITED STATES PATENTS2,486,503 Stephens Nov. l, 1949 2,711,485 Pennock June 21, 19552,750,517 Baum .Tune l2, 1956 2,772,361 Hiestand Nov. 27, 1956 2,798,164Untermyer July 2, 1957 2,821,636 Jeiierson Jan. 28, 1958 2,849,621 ClarkAug. 26, 1958 2,872,587 Stein Feb. 3, 1959

